1. Field of the Invention
The present invention relates to the field of box-making machines and methods. Specifically, the present invention provides an apparatus and method for supplying a plurality of box sheets or box sheet blanks along belts at predetermined intervals.
2. Description of the Related Art
A conventional device, which is part of a box-making machine, for supplying a box sheet is operative so as to take one box sheet from multiple box sheets stacked in a pile and feed the box sheet into a process for making a box. A typical device for supplying a box sheet comprises plural supply belts and a shutter placed above the supply belts, wherein the shutter has a gap which allows only one box sheet to be sent at a time, and wherein the box sheets are stacked up against the shutter in a pile which is no taller than a top portion of the shutter. The box sheets are sent past the gap one at a time due to a contact resistance or coefficient of friction between the supply belt and the piled box sheets. An interval between each of the sent box sheets (between an end of a previous box sheet and the tip of a following box sheet) is adjusted by placing sending belts next to the lower reaches of the supply belts, wherein the sending belts operate faster than the supply belts.
However, because the sending belts, placed at the lower reaches of the supply belts, operate faster than the supply belts in the conventional device, if only one side of a box sheet is caught by the sending belts, this one side of the box sheet is pulled into the sending belts at a higher speed than the other side of the box sheet. As a result, the box sheet is supplied to the sending belts at an improper angle.
Therefore, in order to prevent the one side of the box sheet from being pulled at a high speed by the sending belt prior to the other side of the box sheet from being pulled, a box sheet supplying device has been developed which operates the sending belts at the same speed as the supply belts and which adjusts an interval between each of the sent box sheets by lifting up the piled box sheets so as to not contact the supply belts.
However, due to the fact that the box-making machines operate at very high speeds, it is difficult to harmonize the lifting up/putting down movement of the piled box sheets with the speed of the supply belts, thereby making it difficult to adjust the interval between each of the sent box sheets, thus resulting in variances from the prescribed intervals of each of the sent box sheets.